A wireless communications channel may cause arbitrary time dispersion, attenuation, and phase shift in a received signal. Channel estimation may be used to form an estimate of the effects of the wireless communications channel from available training data transmitted over the wireless communications channel. Since the training data is known, the effects of the wireless communications channel on the training data may be determined and used to remove the effects of the wireless communications channel from the received signal.
FIG. 1 illustrates a prior art technique of using channel estimation to remove the effects of the wireless communications channel on a received signal. A received signal at a receiver may be expressed as Y=Hx+n, where Y is the received signal, H is the wireless communications channel, x is the transmitted signal, and n is noise. A channel estimation unit 105 may process a received training signal, which is known at the receiver, to produce a model of the wireless communications channel, Ĥ. The model of the wireless communications channel, Ĥ, may be provided to a channel compensation unit 110, where it may be applied to the received signal, Y, to produce a recovered transmitted signal, {circumflex over (x)}.